John Henry Spooner, 76, right, confers with his defense attorney Monday, July 15, 2013, during a break in jury selection for his trial on charges that he fatally shot a black teen last year whom he suspected of breaking into his Milwaukee home and stealing weapons. The case has drawn comparisons to the trial of George Zimmerman, who was acquitted two days earlier of killing Trayvon Martin in Sanford, Fla., last year. (AP Photo/Dinesh Ramde)

MILWAUKEE (AP) — The trial for a Milwaukee man accused of gunning down his 13-year-old neighbor whom he suspected of stealing opened Tuesday with prosecutors promising to show jurors a video of the slaying.

The defendant’s own security cameras captured the May 2012 shooting. Prosecutor Mark Williams said the footage provides “the best piece of evidence” to prove it was 76-year-old John Henry Spooner who killed Darius Simmons outside their homes.

“You’re actually going to see the murder in this case,” Williams told jurors during opening statements. “You’re going see the terror in Darius’ face. You’re going to see how coldblooded and callous Mr. Spooner was.”

The defense has conceded that Spooner fired the fatal bullet into Simmons’ chest as they argued on the sidewalk. But defense attorney Franklyn Gimbel said the two issues at trial will be whether Spooner intended to kill the boy, and whether Spooner was suffering from mental illness that prevented him from knowing right from wrong at the time.

Spooner suspected his young neighbor had broken into his home and stolen guns, according to the criminal complaint. Spooner confronted the teen on the sidewalk two days after the burglary and demanded that he return them. When Simmons denied stealing anything, Spooner shot him once in the chest and fired a second shot as the wounded teen fled into the street, the complaint said.

Richard Martinez, one of the Milwaukee police officers who responded after the shooting, testified that Spooner offered an unsolicited confession upon his arrest. Martinez said he ordered Spooner at gunpoint to drop his weapon and Spooner bent down and laid his handgun on the ground.

Martinez testified that he was handcuffing Spooner when the man said, “Yeah, I shot him,” referring to the teen.

Martinez said Spooner had another bullet in his pocket.

Martinez’s partner, Michael Urbaniak, testified that he and Martinez placed Spooner in the back of a squad car while they investigated the scene. While being detained, Spooner commented that he had reached his breaking point and that his house had been broken into two days earlier, Urbaniak said.

The officer said Spooner claimed he knew the culprits were the kids who lived next door, and that they were part of a black family that recently moved next door and had caused nothing but trouble.

Officer Lori Borchert testified that she responded to the burglary report two days earlier. She said two windows on Spooner’s home were broken and Spooner told her four shotguns were missing.

The day after the burglary, Spooner called Borchert and told her that his surveillance video captured images of the suspects. She said she viewed the video and that it showed two different black teenage males coming from the area of Simmons’ home and moving toward Spooner’s home.

She said she didn’t arrest anyone because there wasn’t enough probable cause. She said the faces on the video weren’t clear, and the teens didn’t appear to be holding any of the missing guns.

Gimbel, who limited his cross-examinations, told jurors during opening statements he intends to raise questions about whether Spooner, who’s charged with first-degree intentional homicide, actually had the requisite intent to commit homicide.

“We will focus on what was Mr. Spooner’s intent when he pointed the gun and pulled the trigger,” Gimbel said.